This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-227512, filed Aug. 11, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a method of cooling a hot plate for heating a substrate and a heat processing apparatus.
In the process of photo-resist processing in semiconductor device fabrication, various kinds of heat processing such as heat processing (pre-baking) after a resist solution is applied on the front face of a semiconductor wafer (hereinafter referred to as xe2x80x9ca waferxe2x80x9d), heat processing (post-exposure baking) after exposure of a pattern is performed, and the like are performed.
Such heat processing is usually performed by a heat processing apparatus. This heat processing apparatus has a disc-shaped thick hot plate made of aluminum in a processing container, and performs heat processing for the wafer by placing the wafer to be processed on the hot plate and heating the hot plate to a predetermined temperature by a heating element incorporated in the hot plate.
Incidentally, there are cases where temperatures in heat processing are different, for example, the wafer is heated to 140xc2x0 C. or the wafer is heated to 90xc2x0 C. lower than this temperature, depending on the types of semiconductor devices to be formed, types of resist solutions, and types of processes, and the like. In these cases, for example, when the hot plate which have been performing heat processing at 140xc2x0 C. up to the present is used for heat processing at 90xc2x0 C., it is required to temporarily lower the temperature of the hot plate, for example, to 90xc2x0 C., in which case a conventional heat processing apparatus of this type is not specially equipped with a mechanism for cooling and the like, and thus the hot plate is cooled naturally.
However, if cooling is left only to natural cooling when the hot plate is cooled to the predetermined temperature, the temperature in the surface of the hot plate is lowered in a ununiform state, and a considerably long time is required for reaching the predetermined temperature and obtaining uniform surface temperature, which is undesirable. To improve this, if dedicated heat processing apparatus are previously prepared for respective processing temperatures, for example, 140xc2x0 C. and 90xc2x0 C., a problem of cooling time can be settled, but if so, a large number of heat processing apparatus become necessary, and as a result, a coating and developing apparatus in which usually a various kinds of resist processing apparatus are put together and used is enlarged, which is undesirable.
It is an object of the present invention to provide a method capable of cooling a hot plate of a heat processing apparatus more rapidly than in a conventional method, and a heat processing apparatus having a function capable of suitably carrying out the cooling method.
According to a first aspect of the present invention, there is provided a hot plate cooling method comprising the steps of heating a hot plate for placing a substrate thereon and heating the substrate, and positioning an object whose portion facing the hot plate has a color with good heat absorption efficiency above the hot plate.
According to the aforesaid structure, the object of which the portion facing the hot plate has a color with good heat absorption efficiency is positioned above the hot plate, whereby radiant heat from the hot plate can be effectively absorbed, resulting in the promotion of cooling of the hot plate and uniform cooling.
According to a second aspect of the present invention, there is provided a heat processing apparatus comprising a hot plate for heating a substrate, and a nozzle for blowing cooling gas onto the rear face of the hot plate.
According to the aforesaid structure, the temperature of the hot plate can be lowered more rapidly than in the conventional apparatus, and moreover dust and the like do not adhere to a substrate mounting face since air is blown onto the rear face side of the hot plate.
According to a third aspect of the present invention, there is provided a heating processing apparatus comprising a hot plate for heating a substrate, and an object moving freely over the hot plate whose face opposite the hot plate has a color with good heat absorption efficiency.
According to the aforesaid structure, the object whose portion facing the hot plate has a color with good heat absorption efficiency can be positioned above the hot plate, whereby radiant heat from the hot plate can be effectively absorbed, resulting in the promotion of cooling of the hot plate and uniform cooling.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.